scan.js•906 B
var _curry3 = require('./internal/_curry3');
/**
* Scan is similar to reduce, but returns a list of successively reduced values
* from the left
*
* @func
* @memberOf R
* @since v0.10.0
* @category List
* @sig (a,b -> a) -> a -> [b] -> [a]
* @param {Function} fn The iterator function. Receives two values, the accumulator and the
* current element from the array
* @param {*} acc The accumulator value.
* @param {Array} list The list to iterate over.
* @return {Array} A list of all intermediately reduced values.
* @example
*
* var numbers = [1, 2, 3, 4];
* var factorials = R.scan(R.multiply, 1, numbers); //=> [1, 1, 2, 6, 24]
*/
module.exports = _curry3(function scan(fn, acc, list) {
var idx = 0;
var len = list.length;
var result = [acc];
while (idx < len) {
acc = fn(acc, list[idx]);
result[idx + 1] = acc;
idx += 1;
}
return result;
});